In recent years, computers used for, for example, servers have been mounted with a management unit directed to, for example, condition monitoring, configuration-information displaying, or error-information displaying for hardware. For a computer that is in a stand-by state, the management unit performs system checks on various pieces of hardware, e.g., a CPU (Central Processing Unit), a memory, a fan, and an IO (Input/Output) apparatus. The management unit controls power activation performed by a power supply unit (PSU) in the shifting of a computer from a stand-by state to an in-operation state, and controls power deactivation performed by the PSU in the shifting of the computer from the in-operation state to the stand-by state. In this way, the management unit is operated for both the stand-by state and the in-operation state of the computer. Accordingly, as a PSU for a computer with a management unit, a PSU that includes a dual-system power conversion circuit capable of always supplying power to the management unit and supplying power to each piece of hardware of the computer on an as-needed basis is typically used.
FIG. 1 illustrates a power supply to a computer performed by a conventional PSU.
A PSU 1 in FIG. 1 may supply power to a computer 10 that includes a management unit 16 and various pieces of hardware such as a CPU 11, a memory module (indicated as a “DIMM” (Dual Inline Memory Module) in FIG. 1) 12, an IO apparatus 13, a fan 14, and a disk apparatus 15. The PSU 1 includes two power conversion circuits 2 and 3 intended for different voltages so that power can be supplied to the various pieces of hardware 11-15 on an as-needed basis and so that power can always be supplied to the management unit 16. The power conversion circuits 2 and 3 convert AC power supplied from outside via an outlet 4 into DC power. “V” and “VSB” in FIG. 1 indicate power supplied from the power conversion circuits 2 and 3, respectively.
The configuration of the computer depicted in FIG. 1 is an example, and the configuration of the computer is not limited to the one in FIG. 1. FIG. 1 indicates that power V and power VSB are directly supplied to the various pieces of hardware 11-15 and the management unit 16, respectively, but, in many cases, a DC-DC converter (hereinafter referred to as a “DDC”) is prepared for each piece of hardware. Hence, power is supplied to each of the pieces of hardware 11-15 via a corresponding DDC.
The power conversion circuit 3 is a resident power supply that always generates power VSB in a situation in which AC power is supplied. The power conversion circuit 2 is a non-resident power supply for which the management unit 16 controls the supply of AC power. The power conversion circuit 2 is controlled to supply power V to each part of the computer 10 when the computer 10 is in an in-operation state and to not supply power V when the computer 10 is in a stand-by state.
In recent years, many data centers have been established in which many computers are set up as servers. Many CPUs have been installed in a computer, thereby advancing CPU speeding up. With CPU speeding up, the actual situation is that cooling devices such as fans have become indispensable. Hence, power consumption per computer has tended to increase. Accordingly, a huge power is generally consumed at data centers where many computers are set up.
A PSU that supplies power to a computer also consumes power. Due to increased power consumption by computers, power consumption by the PSU is becoming not negligible. This means that consideration needs to be taken to suppress power consumption by PSUs, which are widely used to supply power to a computer.